Device for extruding a polymer frame onto a plate-shaped object

ABSTRACT

This invention concerns a device used in the process of manufacturing an automobile pane  1  equipped with a polymer frame  52  placed on the edge of the pane  1.  The frame  52  is extruded onto the pane  1  which can be moved by means of a suitable support in such a way that the edge of the pane travels through a recess in an extrusion head  25  and  40.  The recess of the extrusion head  40  preferably includes a U-shaped jaw  41  straddling the edge of the pane. At the front extremity of the two half-jaws of the U-shaped jaw  41  there are disposed sealing ledges or shoes  42  and  43  which are movable perpendicularly to the surfaces of the pane and which, during extrusion, bear upon the surfaces of the pane. Alternatively, the extrusion head can include a fixed jaw where the sealing ledges or shoes slideably and sealingly contact the plate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/286,725 filed Aug. 5, 1995 now U.S. Pat No. 5,507,994.

TECHNICAL FIELD

This invention concerns a device for extruding a profiled cord ofpolymer onto the periphery of an essentially state-shaped object, inparticular onto the periphery of a pane. The device comprises anextrusion head in relative displacement along the edge of the plate,where it deposits a profiled cord composed of a polymer at the outletfrom a calibrated nozzle. The invention concerns, more specifically, thecase in which the plate is moved while the extrusion head has onlyreduced mobility and is generally retained in a fixed position.

BACKGROUND OF THE INVENTION

It is known in the art to utilize various devices for depositing aprofiled frame onto the periphery of a pane, such as an automobileglazing. These devices comprise supporting and displacing elements forthe pane onto which the profiled frame is to be deposited with therelative movement between pane and extrusion head along the edge of thepane being produced to place the frame on the peripheral edge of thepane. The relative movement along the edge is produced by displacementof one of the extrusion head or the pane, for example, by a robot. Ineither case, the head is supplied with fluid polymer from a reservoir.When the head moves relative to the pane, the supply of polymeraccompanies its movement or is connected to the head by a flexible pipeconnected to a fixed distributor. Movement of the edge of the panerelative to a fixed extrusion head is described in European PatentApplications EP-0 585 129 and EP-0 493 068. Many documents describe thetechnique of extrusion of a polymer frame onto the periphery of a plate,such as European Patent Applications EP-A-121 481 and EP-A-524 092.

The thickness tolerances of the panes are not negligible and it istherefore necessary for the extrusion heads of the above type to acceptthe thickest panes of a given type (i.e., an upper limit of thetolerance on the thickness). However, for all the panes of a smallerthickness, the fluid polymer can escape during extrusion through theslot or slots left free between the wall faces of the extrusion head andthe surfaces of the pane. A deposit is thus left on the pane afterextrusion, which must be removed in a supplementary phase of theproduction process.

Since the tolerance of automobile panes is not precisely controlled bythe pane manufacturer, it is difficult to precisely place a polymerframe on the edge of the pane. To avoid this problem. U.S. Pat No.5,183,612 discloses the deposition of the polymer frame onto a dummywindshield which has controlled dimensions. After the frame has cured,it is removed from the dummy windshield and then placed on the glasspane. Also, the polymer frame must be bonded to the glass pane whenplaced thereon. This process is cumbersome and results in duplicativeoperation as well as handling and storage problems for the cured polymerframe.

Another difficulty of prior art devices is that a secure seal to thepane is not always achieved. This can result in the escape of polymerfrom between the seal and the glass surface. Furthermore, movementbetween the die head and the pane becomes difficult if the seal betweenthe die head and the pane is too strong. The present invention resolvesthese problems in a simple yet efficient manner.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for producing a shapedpolymer frame on a plate having top and bottom main surfaces and aperipheral edge. The apparatus further comprises an extrusion die havinga body which defines a plate-receiving recess for receiving the edge ofthe plate and portions of the main surfaces adjacent thereto; a firstsealing ledge which is movable between (1) a retracted position whichallows entry of the plate edge into the recess, and (2) an engagedposition in contact with one of the main surfaces of the plate, whereinan open area is defined between the die body, sealing ledge and theplate in the shape of the polymer frame; and means for moving the platerelative to the extrusion die, where the moving means advances the edgeof the plate through the recess to receive the shaped polymer frame onthe edge and one of the main surfaces of the plate.

This embodiment also may include moving the first sealing ledge betweenthe retracted and engaged positions in a direction which is essentiallyperpendicular to the main surfaces of the plate. The moving meanspreferably comprises spring means for biasing the first sealing ledgetoward the engaged position and rod means for returning the firstsealing ledge to the retracted position. The recess can include a firstsurface which is spaced from the plate and a second surface whichcontacts the plate on the surface opposite that which is contacted bythe first sealing ledge in the engaged position, so that the polymerframe is provided on the edge and a portion of one main surface of theplate. Alternatively, the device can also include a second sealing ledgewhich is movable between (1) a retracted position which allows entry ofthe plate edge into the recess, and (2) an engaged position in contactwith the other main surface of the plate, and the recess can includefirst and second surfaces which are spaced from the plate, so that thepolymer frame is provided on the edge and a portion of each main surfaceof the plate.

Advantageously, the portions of the first sealing ledge and recess whichcontact the plate include a layer of an elastic material thereon tofacilitate sliding movement upon the plate. Also, one or both of thesealing ledges can include an arcuate surface which assists in theformation of an arcuate portion for the polymer frame. The apparatus mayalso include a support wheel which travels along the surface of theplate and compensates for shape tolerances of the plate.

Another embodiment of the invention relates to an apparatus forproducing a shaped polymer frame on a plate having top and bottom mainsurfaces and a peripheral edge. The apparatus further comprises anextrusion die having a one-piece body that defines a plate receivingrecess for receiving the edge of the plate and portions of the mainsurfaces adjacent thereto. The plate receiving recess comprises firstand second sealing ledges which slidingly engage the main surfaces ofthe plate. An open area is defined between the die body, sealing ledgesand the plate in the shape of the polymer frame, and the sealing ledgesprovide a seal for the recess and facilitate sliding movement betweenthe die body and the main surfaces. The apparatus also includes meansfor providing relative movement between the die and plate, such that theedge of the plate advances through the recess to receive the shapedpolymer frame on the edge and at least one of the main surfaces of theplate.

In this embodiment, the portions of the sealing ledges that contact theplate include a layer of an elastic material, such as a thermoplastic,elastomeric, or thermoplastic coated elastomeric foam, thereon tofacilitate the sliding movement. The elastic material has means forreleasably securing the layer of elastic material to the sealing ledgeto facilitate replacement of the layer. The releasable securing meanspreferably comprises a backing member for the elastic material. Thebacking member preferably includes a rib member for engaging acorresponding slot in the sealing ledge. Advantageously, the backingmember is made of an engineering thermoplastic which has sufficientrigidity to retain the rib member in the slot, and the elastic materialis secured to the backing member by a suitable adhesive. Furthermore,the extrusion die may include two channels for supplying polymer to theopen area and means for independently regulating the flow of polymer ineach channel to facilitate the extrusion of the polymer through the openarea and onto the plate.

Yet another embodiment of the invention relates to a process forproducing a shaped polymer frame on a plate having top and bottom mainsurfaces and a peripheral edge. The process comprises placing anextrusion die adjacent the plate edge, wherein the extrusion die has abody which defines a plate-receiving recess for receiving the edge ofthe plate and portions of the main surfaces adjacent thereto and a firstsealing ledge which is movable between (1) a retracted position whichallows entry of the plate edge into the recess, and (2) an engagedposition in contact with one of the main surfaces of the plate. An openarea is defined between the die body, sealing ledge and the plate in theshape of the polymer frame that receives the plate edge in the recess ofthe extrusion die. The process additionally moves the first sealingledge into contact relation with at least one of the main surfaces ofthe plate, advances the plate edge through the recess and depositspolymer onto the plate edge and a portion of at least one of theadjacent main surfaces through the open area of the die during movementof the plate edge through the recess to provide the polymer framethereon.

In this method, the polymer may be a moisture-hardening reaction polymerwhich is deposited upon the peripheral edge of the plate as it advancesthrough the recess. The first sealing edge preferably moves in adirection which is essentially perpendicular to the main surfaces of theplate and is biased towards the engaged position and the method furthercomprises returning the first sealing ledge to the retracted positionafter deposition of the polymer frame. The extrusion die may alsoinclude a second sealing ledge which is movable between (1) a retractedposition which allows entry of the plate edge into the recess, and (2)an engaged position in contact with the other main surface of the plate,and the method further comprises moving the second sealing ledge intocontact relation with the other main surface of the plate before theplate edge is advanced through the recess. Each sealing ledge may bebiased towards the engaged position and the method further comprisesreturning each sealing ledge to the retracted position after depositionof the polymer frame.

The moisture hardening reaction polymer preferably comprises athermoplastic polyolefin elastomer constituted by isotacticpolypropylene and ethylene propylene diene rubber. Also, the elasticmaterial is preferably selected from the group consisting ofthermoplastic foam, elastomeric foam, and thermoplastic coatedelastomeric foam.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention can be gathered fromthe claims and the following description with respect to the attacheddrawings, wherein:

FIG. 1 illustrates a form of the embodiment of an extrusion head forextrusion of a polymer frame of L-section;

FIG. 2 shows a form of embodiment of an extrusion head for placing bythe extrusion of a frame of U-section straddling the edge of the pane;

FIG. 3 shows a detail of an extrusion head in accordance with thisinvention;

FIG. 4 is an illustration of a robot which can be used for moving theedge of the glass pane past the extrusion head;

FIG. 5 illustrates another form of the embodiment of an extrusion headhaving fixed mouth jaws; and

FIG. 6 illustrates a preferred configuration for the elastic member andits attachment to the sealing ledges.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention has as its objective to produce an extrusion head thatwill make possible the extrusion of a polymer onto the periphery of aplate, such as an automobile pane, for the purpose of producing aprofile which rests on the edge face of the pane and on at least one ofits main faces. Independently of the variations in thickness of thepane, the extrusion head must allow a proper and geometrically accuratetransition to be made between the profiled member and the face or facesof the pane.

The invention proposes a device for extruding a profiled cord of polymeronto the periphery of a plate, in particular an automobile pane. Thedevice comprises an extrusion head in relative displacement along theperiphery of the plate, against the edge face of which it bearsupstream, at the same time as at least one half-jaw bears on a main faceof the plate. The downstream wall aft of the extrusion head comprised ofan extrusion nozzle, the orifice of which is bounded, amongst otherthings, by the surface of the plate itself and by its edge face, inwhich device a supporting and conveying system is provided for the plateand in which the half-jaw of the extrusion head in bearing against themain face of the plate comprises a shoe movable perpendicularly to thisface of the plate which, during extrusion, is pressed onto the plate.

In a variation of the invention, the extrusion head comprises a jaw, onehalf-jaw of which is equipped with a movable shoe, while the otherhalf-jaw has its surface in contact with the surface of the plate, thishalf-jaw surface extending in the continuity of the plate surface. It isalso provided that the extrusion head comprises a jaw, the two half-jawsof which are equipped with shoes movable perpendicularly to the surfacesof the plate which, during extrusion, are pressed onto these surfaces,and preferably the surfaces of the extrusion head pressed onto thesurfaces of the plate are equipped with a layer of an elastic memberhaving good sliding properties on the surfaces of the movable plate.

The elastic member is preferably a foam that has sufficientcompressibility to allow insertion and removal of the glass pane, aswell as a relatively low friction surface to facilitate sliding movementover the glass. A preferred construction is a neoprene foam thatincludes a teflon coating on the external surface that contacts theglass. The low friction coating is not critical, as certain highperformance foams provide sufficient surface properties to facilitatethe sliding movement of the glass. Thus, other materials that can beprocessed into a foam can be used, such as polyurethanes,thermoplastics, such as polyvinyl chloride, or elastomers, such asrubber. When desired, other fluoropolymers or nylon can be used as thelow friction coating. The coating can be applied to the foam in any oneof a number of conventional manners which need not be described in anyfurther detail herein.

In the embodiment of FIGS. 1-3, the sealing ledges will form a seal onthe pane whether the pane is movable or fixed in relation to theextrusion die. The provision of movable sliding lateral shoes or sealingledges, allows the formation of a relatively tight seal on the paneduring extrusion of the polymer, but also the easy insertion or removalof the pane before and after the time that the polymer is extruded. Thesealing ledges are pressed onto the surfaces of the glass during therelative displacement of the extrusion head and the pane by means ofsprings, but which, at the instant at which the pane is placed inposition or to be removed, are moved away by jacks so as to permit thefree movement of the pane through the jaw which constitutes theextrusion head. In fact, it is possible to adjust the position of theextrusion head relative to the edge of the plate such that one side ofthe jaw shall always be in contact with the corresponding surface of thepane, while the other comprises the sliding shoe. The purpose of thesliding shoe is to follow the surface during the relative longitudinaldisplacement of the extrusion head and pane during the extrusion and torelease passage at the start and the end of the operation when therelative displacement takes place perpendicularly to the edge of thepane.

A head of the foregoing type is advisable, principally, in those casesin which the cord to be extruded has an L-profile which is, at one ofthe ends of its cross-section, in continuity with the surface of thepane. Such cords are desired, for example, when automobile panes must bemounted flush with the bodywork for aerodynamic reasons. In this case,the extrusion head should be constructed so that the upstream wall faceof its head shall be in contact with the surface of the pane as far asits edge face and shall radially continue, in an outward direction, tothe main surface of the pane. It is also possible to construct theextrusion head so as to obtain a frame which encompasses or grips theedge of the pane on its three faces. The extruded frame may then, inprinciple, have any cross-section.

The description that follows concerns the invention in the case whereframes are placed by extrusion on panes, in particular automobile panes.The extrusion head of this invention, however, enables other objects ofplate-shape or comprising a plate, such as doors or constructionelements, to be equipped with frames or appropriate seals.

An extrusion head according to this invention in particularadvantageously enables thermoplastic polymers to be extruded onto theedge of various plates, in particular panes. As thermoplastic polymermay be used, for example, thermoplastic polyolefin elastomers ofisotactic polypropylene and ethylenepropylene-diene rubber. In the useof thermoplastic polymers, it is indicated to heat the panes. Forexample, at a temperature of approximately 150° C., the thermoplasticpolymer is melted in an extruder and is fed to the extrusion head eitherdirectly, if the head is fixed, or by means of a pressure-resistant,heating flexible tube if it is movable. However, instead ofthermoplastic polymers, it is possible to use reactive substances, forexample, reactive components for humidity-hardening polyurethanes. Inthis case, the extruder is replaced by a suitable pump, which suppliesthe material to be extruded to the extrusion head.

When the extrusion head and the pane, after the extrusion has beendeposited around the entire pane, have returned to their startingpositions, the volume flow of the polymer is interrupted, the pane ismoved away from the extrusion head and the pane, provided with theframe, is brought to the next working station, while at the same timeanother pane is brought into the extrusion station. The extrusion cyclethen recommences.

The transition point between the start and the end of the extrudedpolymer cord inevitably has deformations, because of the radialdisplacement of the pane at the end of the extrusion operation. Thistransition point must therefore be retouched during the operation whichfollows. The retouching of the transition point may be carried out, forexample, in accordance with one of the processes forming the subject ofdocuments EP 0 421 833 or EP 0 524 060. The retouching of the transitionzone is particularly simple if a thermoplastic polymer is extruded,because in this case all that is necessary is to perform a finishingpressing using a heated pressing tool.

FIG. 1 shows the basic structure of an extrusion head used when a pane 1is to be provided with a polymer frame 20 which, on one side of the panethat is the side of the main surface 21, continues this surface 21 byits own surface, at the same level, but for the remainder has anL-shaped section, the flanges of the profile being in contact,respectively, with the main surface 22 and with the peripheral edge face23 of the pane and being firmly fixed to the surface of the glass. Themethods of functioning of the extrusion head of FIG. 1 are various. Theybelong to two principal groups, in which either the pane is fixed andthe extrusion head, moved manually or under control of a robot, travelsalong the periphery of the pane or, conversely, the pane is moved pastthe extrusion head, which is slightly or not at all movable.

In this latter case, which is of particular interest in this invention,and, when the glass is curved, several cases can arise:

the extrusion head is fixed and it is the pane that is moved by a robotso that the edge at which the extrusion is to be performed is at thecorrect place and in the correct direction, that is with the convex faceof the curvature tangential to one wall face of the jaw of the extrusionhead;

the pane is travelling in translation without changing its orientationrelative to this plane. Its edge travels along the perpendicular to theextrusion head and the head, movable vertically, can pivot so that itsjaw remains tangential to the edge of the pane; intermediate situationsare also possible, with the pane, the edge of which is in rectilinearlateral displacements in front of the head, which pivots to have thecorrect orientation.

The extrusion head 25 has a jaw 26 with a U-section, which extends inthe direction of the displacement, into which jaw engages the edge ofthe pane 1. This jaw 26, of U-shape, is bounded on the lower side by thehalf-jaw 27, the upper surface 28 of which, during the extrusionoperation, is in contact with the main surface 21 of the pane 1. On theupper side, the jaw 26 of the extrusion head is formed by the half-jaw29.

In the downstream wall face of the extrusion head is the calibratedorifice of the nozzle, which determines the cross-section of theextruded polymer cord. The aperture of the U of the extrusion head isbounded by the wall face 30 of the movable shoe 31. This shoe 31 ismounted so that it is movable in the vertical direction. It can beraised by means of the rod 32, by use of the pneumatic or hydraulic jack33. In the lowered position, the shoe 31 is pressed against the surface22 of the pane 1 by helical springs 34 or other means producing the sameeffect. The bearing force exerted by the springs 34 must be adjusted insuch a way that a good seal shall be assured of the surfaces of theextrusion head 25 that slide on the two main faces of the pane 1. On theother hand, the bearing pressure must not be too great so that thefriction forces do not become too high during the extrusion operation,which could, on the one hand, interfere with the relative movement ofthe head and pane and, on the other hand, wear the sliding surfaces ofthis head.

The jack 33, which actuates the sealing shoe 31, is governed by acentral control unit. The sealing shoe 31 is brought into its upper, endposition by means of the jack 33 when the extrusion head-pane assembly25 is displaced from its at-rest position to its working position andwhen both, at the end of the extrusion operation, are brought back intotheir at-rest position, separated from each other.

On each of the sliding surfaces of the extrusion head 25, that is thesurface 28 of the half-jaw 27 and the lower face of the shoe 31, thereis disposed a lining 35 and 36, made of an elastic material having goodsliding properties with respect to glass. These linings 35 and 36 servefor improving the seal of the extrusion chamber at the position of thesurfaces of the pane, for accepting variations in curvature of the plateand for facilitating sliding. As noted above, a teflon coated neoprenefoam is advantageous for use as these linings. Furthermore, theselinings 35 and 36 are advantageously mounted so that they can be rapidlyreplaced when necessary. These linings may, for example, be removablymounted parallel to the edge of the pane, such that the movement of theplate relative to the die would not move the mounted lining.Additionally, these linings may be mounted to the extrusion die by meansof fasteners that are recessed from the surface of the lining so as notto make contact with the pane.

The extrusion head 40 shown in FIG. 2 is basically made in analogousmanner to the head 25 described in relation to FIG. 1, but it isdistinguished by the fact that the two half-jaws 50 and 51, which boundthe U-section jaw 41, comprise movable sealing shoes 42 and 43. Thesealing shoes or ledges 42 and 43 are in the present case also pressedagainst the two principal surfaces of the pane 1 by helical springs 44.The pneumatic or hydraulic jacks 45 and 46 bring the sealing shoes, bymeans of rods 47 and 48, into their final opened position, when theextrusion head is brought from its waiting position relative to itsworking position on the edge of the pane and when, at the end of theextrusion operation, the head 25 and the pane 1 move apart from oneanother. Replaceable linings 49, made of an elastic material having goodsliding properties with respect to glass, are also mounted on thesliding surfaces of the two sealing shoes 42 and 43.

The extrusion head 40 is suitable for the extrusion of a profiled cord52 which fits around the peripheral part of a pane, on its edge face andits two main faces, with a U-section. FIG. 3 shows an extrusion head 55constructed on the principle described above, in its working position inwhich the calibrated orifice of the nozzle 56 of the extrusion head issupplied, with polymer to be extruded, through two separate ducts 57 and58. The polymer flow rate in each of these ducts can be regulatedseparately by appropriate throttling devices installed in these ducts orin pipes that supply them with polymer. It thus becomes possible tosupply, at different parts of the cross-section of the orifice 56 of theextrusion head, different volumetric flow rates if, as in the caseillustrated, the cross-section of the profile 60 of the frame is notsymmetrical and, consequently, a larger quantity of material isnecessary in one part of the orifice of the die than in another part.Another, case in which it is advantageous to meter material intended forthe inner part and the outer part of the profile at different flow ratesis the production of curves of the extruded profile in the corners ofthe plate, and especially of the pane.

In FIG. 3, there is also shown a bearing wheel 62, which is mounted onthe extrusion head carrying the nozzle 55, by means of a support 63.This bearing wheel 62 serves for compensating the tolerances of shape ofthe pane 1 in the direction perpendicular to the surface of the pane, inparticular in the case of curved panes. For this purpose, the extrusionhead is mounted so that it can move a few millimeters in the verticaldirection, in such a way that the compensation necessary for thetolerances is performed by means of the bearing wheel 62.

FIG. 4 illustrates a robot that can be used for moving the edge of theglass pane past the extrusion head. In FIG. 4 there is shown a robotwith a supporting member 66 fixed to the floor containing conventionalmeans for moving the robot's swivel member 67, rotating forwardly andreversedly shafts 76, 77, 79, 81, 82, 88, and 90, and arms 74, 75, 78,80, and 93. A panel suction unit 86 is attached to the arm 80 by meansof a mounting member 85, and is used to provide suction through the fourorthogonal arms 93 to the four suction cups 94 used to support the pane1. Supporting arm 92 rotates the plate by means of shaft 90 through themouth 41 of the relatively fixed extrusion head 25, which is itselfattached to a support 65. As such robots are generally know, no furtherdescription needs to be included here. Despite that such robots areknown, it is the novel extrusion heads of the present invention whichenable the deposition of uniform, acceptable profile frames upon theglass surfaces of the panes.

It is also optionally possible, however, to use an extrusion die withrigidly positioned sealing ledges. This presupposes that the glassplates to be provided with the polymer frame have very small thicknesstolerances and that the internal dimensions of the die mouth are veryaccurately matched to the thickness dimensions of the glass plates. Thegap between a sealing face of the extrusion die and the glass surfacecan vary between approximately 0.1 and 0.5 mm depending upon theviscosity and related characteristics of the polymer which is used. Inthis mode, the foam of the elastic material compresses as the plateenters the jaw of the extrusion die to form the seal. For example, thefoam may be angled to create a wedge-shaped recess into which the panemay enter from the wider end of the wedge. Upon entry of the pane fullyinto the recess, the pane will compress the foam and create a seal.

In the case of extrusion dies that have a rigid die mouth, the extrudedpolymer strand can be removed by movement of the die when the die isremoved from the glass plate at the end of the extrusion operation.However, the frame profile can be reshaped at this point in aproblem-free manner according to known methods.

FIG. 5 illustrates another form of the embodiment of an extrusion head40 having two fixed mouth jaws each having an elastic layer 49. The pane1 slides along the mouth 41 of the extrusion die 40. The upper surface22 and lower surface 21 of the pane 1 slide through the fixed mouth jawswith an elastic layer 49, receiving a polymer frame 52 upon the pane'sedge 23 and at least one main surface. As noted above, a wedge shape canbe provided on each sealing ledge to facilitate insertion of the plateinto the recess.

FIG. 6 illustrates a preferred arrangement for fastening the elasticmaterial to the sealing ledge. Lining 35 includes elastic material 70and low friction coating 71. The elastic material is attached to abacking member 72 by a suitable adhesive for the materials used. Thebacking member is preferably made of an engineering thermoplastic, suchas nylon, polycarbonate, or the like, so that it can provide sufficientstrength to join the lining to the sealing ledge.

In a most preferred embodiment, the backing member 72 includes a ribmember for engaging a corresponding slot in the sealing ledge. Thisallows the arrangement to be easily installed or replaced when the lowfriction coating or elastic material becomes worn or damaged. Inaddition, the backing member can be re-used, and a new lining placedthereon for future use. This arrangement can be used on either the fixedjaw or movable jaw embodiments, on one or preferably both of the sealingledges.

Although the preceding embodiments represent preferred aspects of theinvention, the true scope is not to be limited except as recitedliterally in the following claims and including all modifications whichare equivalent or obvious to one of ordinary skill in the art.

What is claimed is:
 1. An apparatus for producing a shaped polymer frameon a plate having top and bottom main surfaces and a peripheral edge,which comprises: an extrusion die having a body which defines aplate-receiving recess for receiving the edge of the plate and portionsof the main surfaces adjacent thereto; a first sealing ledge which ismovable between (1) a retracted position which allows entry of the plateedge into the recess, and (2) an engaged position in contact with one ofthe main surfaces of the plate which defines an open area between thedie body, sealing ledge and the plate in the shape of a polymer frame;and means for moving the plate relative to the extrusion die, where themoving means advances the edge of the plate through the recess toreceive the shaped polymer frame on the edge and one of the mainsurfaces of the plate.
 2. The apparatus of claim 1 which furthercomprises means for moving the first sealing ledge between the retractedand engaged positions in a direction which is essentially perpendicularto the main surfaces of the plate.
 3. The apparatus of claim 2 whereinthe moving means comprises spring means for biasing the first sealingledge toward the engaged position and rod means for returning the firstsealing ledge to the retracted position.
 4. The apparatus of claim 1wherein the recess includes a first surface which is spaced from theplate and a second surface which contacts the plate on the surfaceopposite that which is contacted by the first sealing ledge in theengaged position, so that the polymer frame is provided on the edge anda portion of one main surface of the plate.
 5. The apparatus of claim 4wherein the portions of the first sealing ledge and recess which contactthe plate include a layer of an elastic material thereon to facilitatesliding movement upon the plate.
 6. The apparatus of claim 1 whichfurther comprises a second sealing ledge which is movable between (1) aretracted position which allows entry of the plate edge into the recess,and (2) an engaged position in contact with the other main surface ofthe plate.
 7. The apparatus of claim 6 wherein one or both of thesealing ledges includes an arcuate surface which assists in theformation of an arcuate portion for the polymer frame.
 8. The apparatusof claim 6 wherein the recess includes first and second surfaces whichare spaced from the plate, so that the polymer frame is provided on theedge and a portion of each main surface of the plate.
 9. The apparatusof claim 1 which further comprises a support wheel which travels alongthe surface of the plate and compensates for shape tolerances of theplate.
 10. An apparatus for producing a shaped polymer frame on a platehaving top and bottom main surfaces and a peripheral edge, whichcomprises: an extrusion die having a one-piece body which defines aplate receiving recess for receiving the edge of the plate and portionsof the main surfaces adjacent thereto; said plate receiving recesscomprising first and second sealing ledges which are movable between (1)a retracted position which allows entry of the plate edge into therecess, and (2) an engaged position in contact with the main surfaces ofthe plate which defines an open area between the die body, sealingledges and the plate in the shape of a polymer frame, wherein thesealing ledges, in the engaged position, provide a seal for said recessand facilitate sliding movement between said die body and said mainsurfaces; and means for providing relative movement between the die andplate such that the edge of the plate advances through the recess toreceive the shaped polymer frame on the edge and at least one of themain surfaces of the plate.
 11. The apparatus of claim 10 wherein theportions of the sealing ledges that contact the plate include a layer ofan elastic material thereon to facilitate said sliding movement.
 12. Theapparatus of claim 11 which further comprises selecting the elasticmaterial from the group consisting of thermoplastic foam, elastomericfoam, and thermoplastic coated elastomeric foam.
 13. The apparatus ofclaim 12 which further comprises means for releasably securing the layerof elastic material to the sealing ledge to facilitate replacement ofsaid layer.
 14. The apparatus of claim 13 wherein the releasablesecuring means comprises a backing member for the elastic material, withthe backing member including a rib member for engaging a correspondingslot in the sealing ledge.
 15. The apparatus of claim 14 wherein thebacking member is made of an engineering thermoplastic having sufficientrigidity to retain the rib member in the slot.
 16. The apparatus ofclaim 15 wherein the elastic member is secured to the backing member byan adhesive.
 17. The apparatus of claim 10 wherein the recess includes afirst surface which is spaced from the plate and a second surface whichcontacts the plate on the surface opposite that which is contacted bythe first sealing ledge, so that the polymer frame is provided on theedge and a portion of one main surface of the plate.
 18. The apparatusof claim 10 wherein the recess includes first and second surfaces whichare spaced from the plate, so that the polymer frame is provided on theedge and a portion of each main surface of the plate.
 19. The apparatusof claim 10 wherein one or both of the sealing ledges includes anarcuate surface which assists in the formation of an arcuate portion forthe polymer frame.
 20. The apparatus of claim 10 wherein the extrusiondie includes two channels for supplying polymer to the open area andmeans for independently regulating the flow of polymer in each channel.21. The apparatus of claim 10 which further comprises means forextruding the polymer through the open area and onto the plate.
 22. Aprocess for producing a shaped polymer frame on a plate having top andbottom main surfaces and a peripheral edge, which process comprises:placing an extrusion die adjacent the plate edge, wherein the extrusiondie has a body which defines a plate-receiving recess for receiving theedge of the plate and portions of the main surfaces adjacent thereto;and a first sealing ledge which is movable between (1) a retractedposition which allows entry of the plate edge into the recess, and (2)an engaged position in contact with one of the main surfaces of theplate which defines an open area between the die body, sealing ledge andthe plate in the shape of a polymer frame; receiving the plate edge inthe recess of the extrusion die; moving the first sealing ledge intocontact relation with at least one of the main surfaces of the plate;advancing the plate edge through the recess; and depositing polymer ontothe plate edge and a portion of at least one of the adjacent mainsurfaces through the open area of the die during movement of the plateedge through the recess to provide the polymer frame thereon.
 23. Themethod of claim 22 wherein the polymer is a moisture-hardening reactionpolymer which is deposited upon the peripheral edge of the plate as itadvances through the recess.
 24. The method of claim 22 wherein thefirst sealing edge moves in a direction which is essentiallyperpendicular to the main surfaces of the plate and is biased towardsthe engaged position and the method further comprises returning thefirst sealing ledge to the retracted position after deposition of thepolymer frame.
 25. The method of claim 22 wherein the extrusion diefurther comprises a second sealing ledge which is movable between (1) aretracted position which allows entry of the plate edge into the recess,and (2) an engaged position in contact with the other main surface ofthe plate, and the method further comprises moving the second sealingledge into contact relation with the other main surface of the platebefore the plate edge is advanced through the recess.
 26. The method ofclaim 25 wherein each sealing ledge is biased towards the engagedposition and the method further comprises returning each sealing ledgeto the retracted position after deposition of the polymer frame.
 27. Themethod of claim 22 wherein the extrusion die includes two channels forsupplying polymer to the open area and the method further comprisesindependently regulating the flow of polymer in each channel tofacilitate the filling of the open area of the extrusion die.
 28. Themethod of claim 22 wherein the recess includes a first surface which isspaced from the plate and a second surface which contacts the plate onthe surface opposite that which is contacted by the first sealing ledgein the engaged position, and the method further comprises providing thefirst sealing ledge and the second surface of the recess with a layer ofan elastic material thereon to facilitate sliding movement of the platethrough the recess.
 29. The method of claim 25 wherein the recessincludes first and second surfaces which are spaced from the plate sothat the polymer frame is provided on the edge and a portion of eachmain surface of the plate, and the method further comprises providingeach sealing ledge with a layer of an elastic material thereon tofacilitate sliding movement of the plate through the recess.
 30. Themethod of claim 25 which further comprises forming an arcuate portion onthe polymer frame by providing one or both of the sealing ledges with anarcuate surface which assists in the formation of the polymer frame. 31.The method of claim 22 which further comprises compensating for shapetolerances of the plate as the die travels along the plate.
 32. Themethod of claim 23 wherein the moisture hardening reaction polymercomprises a thermoplastic polyolefin elastomer constituted by isotacticpolypropylene and ethylene propylene diene rubber.
 33. The method ofclaim 28 which further comprises selecting the elastic material from thegroup consisting of thermoplastic foam, elastomeric foam, andthermoplastic coated elastomeric foam.
 34. The method of claim 29 whichfurther comprises selecting each elastic material from the groupconsisting of thermoplastic foam, elastomeric foam, and thermoplasticcoated elastomeric foam.